Anti mouse iga hrp

For serum ELISA, MaxiSorb™ ELISA plates (Thermo Fischer Scientific) were coated with 4–8 μg/ml purified influenza virus or approximately 1 × 10¹⁰ vg/ml AAV9 empty capsids in 50 μl 50 mM carbonate/bicarbonate buffer (pH = 9.6) overnight at 4°C. Plates were blocked with 3% skim milk in PBST^0.05% before twofold serum dilutions in 50 μl blocking buffer were added and plates were incubated 90 min at 37°C. For lung homogenate ELISA, plates were coated as mentioned above. Plates were blocked with 1% BSA in PBST^0.05%, before 50 μl of a twofold dilution of lung homogenates in PBST^0.05% was added for 1 h at 37°C. After washing, plates were incubated with anti‐mouse‐IgG‐HRP (1:1,000; Agilent Technologies) or anti‐mouse‐IgA‐HRP (1:1,000; Thermo Fischer Scientific) antibody for 45 min at 37°C before plates were washed again and 1‐Step™ Ultra TMB‐ELISA Substrate Solution (Thermo Fischer Scientific) was added for 1–10 min until color reaction was stopped with 1 M H₂SO₄. Optical density was measured at 450 nm (OD_450 nm), and the area under the curve was determined using GraphPad Prism software.